Stay positive and you will have a happy ending! I wouldn't waste time and energy making any more mistakes. They'll happen themselves whether you want them to or not. Instead use your time and energy in a positive way, to reach for your goals and make that happy ending happen.
Personally, I think I've made more mistakes in my adult years than in my teenage years. The main thing is to embrace your mistakes and learn from them. I'm doing alot more now than I would ever have thought possible a few years ago. I'm older and wiser and don't worry as much now about what people think as I did when I was a teenager. I wouldn't change my teenage years but I wouldn't want to go back to them either.
Good luck with your happy ending. I'm still waiting for mine!